Saturday, November 2, 2013

Heads, We Win!

            The relationship between the head and the mind is a subtle one, and it has led generations of scientists into difficult straits.  The brain is inside the head.  Aside from Aristotle and his most devout followers (who thought the brain's primary function was to cool the body), nearly all ancient and modern European scholars have understood the brain's primary function to be in producing thoughts.  Yet different people have different thoughts - some bad, some good.  And some people have mental gifts - for mathematics, for art, for socializing.  Is it because they have different kinds of brains?  Is it because they have different kinds of heads?

            Perhaps we should look to science to find out.

            In the first half of the 19th century, one of the most popular applied sciences was known as phrenology, developed by medical anatomists.  It answered  the question, "Why do people have such different personalities?" by recourse to medical anatomy.  The logic, primitive if comprehensible, was that people have different personalities because they have different brains; the brain is composed of various modules for music, love, fidelity, and the like, and since the skull encloses the brain, we can read one's personal talents and abilities from the overdeveloped or underdeveloped parts of their brain, which are inscribed upon the surface of the skull.  Just as a home-wrapped Christmas present might contain a bulge for a part that is a bit too large for its box, so too does the skull have bulges corresponding to the overdeveloped parts of the brain governing particular personality attributes.  All we need to do, then, is to feel the bumps on your skull, and we can tell you about your latent abilities.

            By the latter part of the 19th century, this was generally looked upon scornfully by the mainstream anatomical community, which had its own crude logical practice.  Just as a large pancreas secretes more insulin, it stands to reason that a large brain secretes more thoughts.  Thus, people with large brains are more intellectually gifted than people with smaller brains.[1]  One of the strongest early advocates of this idea, Samuel George Morton of Philadelphia in the 1840s, was also a believer in phrenology.  And yet, it was not too difficult to find small-brained geniuses and big-brained dummies.

            Perhaps, then, the head's gross shape had something to do with it, in addition to the head's gross size and surface details, or perhaps instead of them.   Some people (and populations) had long heads; others had short, broad heads.  Standardized measurements and a pompous scientific vocabulary developed in the middle of the 19th century described long-heads as dolichocephalic and broad-heads as brachycephalic.  As descriptions of people, of course, they were fine, but as explanations for their histories and social conditions, they were nonsensical, even if scientifically mainstream.[2] 

            The early anthropologist Franz Boas began to debunk the value of head shape, for any other purpose than descriptive, by empirically contrasting the head shapes of immigrants with the heads of their children and other family members, and showing that this trait was heavily influenced by the environment.[3]  On the other hand, the early physical anthropologist Aleš Hrdlička wrote with dismissive condescension about phrenology, but when given the chance to examine the brain of a recently deceased Eskimo (Inuit) from Greenland, he leapt at the opportunity.  His 1901 paper on "An Eskimo Brain" was not followed by one on "An Eskimo Arm" or "An Eskimo Liver," so he clearly regarded the organ as one of especially great scientific interest.  It is not clear, though, just what he expected to learn from it, although he quite ghoulishly concludes, "The marked differences  ...  from those of the whites  ... makes a future acquisition of Eskimo brains very desirable."[4]

            By the 1920s, it had become clear that culture was not to be found inside people's brains, but rather, constituted a part of the environment that imposed itself upon people's brains.  This is not to say that all brains are identical, but like arms and livers, their differences are largely irrelevant to the question of why different groups of people behave as they do, or have the histories that they do.  In pathological cases, the structure of a brain might be interesting, but it functions pretty much the same way in all normal people, whatever language they speak, and whatever their social background, class, diet, traditions, or values may be.

            By the 1950s, the physical anthropologists had come around as well - to the recognition that measuring head size and shape had its uses, but none of them involved the question of why different groups of people think and act as they do.  The eventual apprehension of this fact was doubtless a consequence of the fact that the physical anthropology of the Nazis, like their human genetics, was not all that different from its American counterpart, and had to be fundamentally reconceptualized after World War II.[5] 

            The head studies, however, required admitting an exception to the guiding principle of anatomy: that form follows function.  The new physical anthropology,[6] christened by Sherwood Washburn in 1951, would finally follow the cultural anthropologists, and hold as axiomatic that variation in mental properties and functions is disconnected from physical variation in head form.  There is a wide range of variation in normal human heads, and a wide range of variation in normal human thoughts, and they only map on to one another in the grossest or crudest of ways.  You can't legitimately infer cultural difference from the observation of cranial difference, nor cultural similarity from the observation of cranial similarity.  The reason is that they are epistemologically disconnected, for cultural differences are the products of history, not biology. 

            Thus, heads are more-or-less interchangeable across the great bulk of our species, and the brains inside them can do pretty much what anyone else's brain can do, except in pathological or exceedingly unusual cases. Consequently, when we encounter a modern human skull in the ethnographic, archaeological, or fossil record, we are going to assume that it housed a normal modern human brain, just like yours and mine, and consequently was capable of thinking the full range of normal modern human thoughts, just like yours and mine.  That seems to be the best inference we can draw from two centuries of studying the anthropology of heads.

[1] There are still a few psychologists who maintain this.  Actually, however, the correlation of IQ with brain size is far lower than the correlation of brain size with body size.  In other words, big people tend to have big brains.  If it were true that brain size were a significant determinant of intelligence, then the smartest people on earth would be football linemen.
[2] Gould SJ (1981) The Mismeasure of Man. New York: W W Norton.
[3] Boas F (1912) Changes in the bodily form of descendants of immigrants. American Anthropologist 14: 530-562
[4] Hrdlicka A (1901) An Eskimo brain. American Anthropologist 3: 454-500.  This was the brain of Qisuk, one of the "New York Eskimos" whom Franz Boas convinced Robert Peary to bring to the Big Apple from the Arctic.  All but Qisuk's son died within a few months.  I discussed this in Chapter 8 of Why I Am Not a Scientist.
[5] Marks J (2010) The two 20th century crises of racial anthropology. In: Little MA, Kennedy KAR, eds. History of Physical Anthropology in the Twentieth Century. Lexington Books Lanham, MD: pp. 187-206.
[6] Washburn SL (1951) The new physical anthropology. Transactions of the New York Academy of Sciences, Series II 13: 298-304